1. Field of the Invention
The present invention relates to an image acquiring apparatus and an image acquiring method, and more particularly, to an image acquiring apparatus and an image acquiring method that are able to detect and recognize size of a scan target during the scanning process without using sensors.
2. Description of the Prior Art
In general, there are two kinds of conventional methods for detecting the size of a scan target (such as a document or a picture) and determining a scanning area in the conventional image acquiring apparatus (such as a flatbed scanner). In the first kind of conventional method, a plurality of sensors (such as infrared sensors) are installed in the conventional image acquiring apparatus for detecting the size of the scan targets. However, when the scan targets may contain sheets of various sizes, more sensors must be installed. This means that the production cost of the image acquiring apparatus by implementing this conventional detecting method will be very high.
In the second kind of conventional method, the conventional image apparatus scans the overall scan window firstly, and then the conventional image apparatus obtains an image of a scan target by using an algorithm. In other words, in this kind of conventional method, the conventional image apparatus processes the data which got from scanning the overall scan window for obtaining the image of the scan target. In this way, the quantity of processed data will be constantly large. Thus, this conventional image apparatus has to use a CPU having higher capability and a faster direct memory access (DMA) controller (this means that using this kind of conventional image acquiring method and related image acquiring apparatus will also cost a lot). Otherwise, the image acquiring apparatus cannot perform the scanning operation efficiently, and missing data will probably occur often.
The image acquiring apparatus and the image acquiring method disclosed by the present invention can detect and recognize the size of the scan target without additional sensors during the scanning process and without being limited by the number of sensors and other factors, while the conventional image acquiring method and the related image acquiring apparatus cost a lot. The image acquiring apparatus and the image acquiring method disclosed by the present invention can perform the scanning operation efficiently without using a CPU having higher capability and a faster direct memory access (DMA) controller, and no data missing conditions will occur.